The present invention relates to a procedure as defined in the preamble of claim 1 for the switching of data traffic in a telecommunication system.
In prior art, at least two methods are known that can be used to connect a subscriber to a local exchange, by connecting the subscriber via a subscriber line directly to the local exchange or to a subscriber module connected to it, or by connecting the subscriber to the local exchange via a separate access network.
Open interfaces V5.1 and V5.2 between an access network, preferably an access node, and a local exchange are defined in the ETSI (European Telecommunications and Standards Institute) standards of the ETS 300 324 and ETS 300 347 series. A V5 interface enables subscribers belonging to a physically separate access network to be connected to a telephone exchange using a standard interface. The V5.2 interface between an access node and a telephone exchange is a concentrator interface. The reservation and/or connection of the transmission path is performed in accordance with the standard by using the BCC protocol. To do this in practice, the BCC protocol component in the local exchange scans and specifies a free time slot in the V5 interface and then transmits a reservation message to the protocol component in the access node. The protocol component in the access node acknowledges receipt of the message.
Connections to narrow-band data networks, especially the Internet, are mainly effected via a telephone network using switched ISDN or PSTN connections (Integrated Services Digital Network; Public Switched Telephone Network). The structure of access networks has been developed by teleoperators on the basis of the so-called zigzag topology. The capacity of access networks is designed on the basis of an estimated average telephone usage (average call duration, allowed congestion).
The switching of data traffic via the telephone network presents new challenges regarding the use of capacity. When an Internet connection is set up via the telephone network using a switched ISDN connection, the duration of the connection and the amount of data transmitted via the connection differ significantly from a normal voice connection. For this reason, collisions may occur and bottlenecks may be formed in remote concentrator units and local exchanges, hampering the switching of telephone and data traffic. A component particularly susceptible to become a bottleneck is the concentrated V5.2 interface between the access node and the local exchange, because its capacity has been defined on the basis of normal telephone traffic.
Based on the V5 standard, a connection to the Internet set up via a switched ISDN or PSTN link is, like a normal call, first connected to the telephone exchange and further from the telephone exchange to the Internet or other data network or to a remote access unit (RAS, Remote Access Server) connected to it, which may be located in a service provider""s station. The remote access unit terminates the ISDN/POTS call setup, takes care of checking the rights relating to call setup and carrying out other corresponding measures before the call is connected to the Internet.
If many subscribers connected to the access node set up a connection to the remote access unit, a situation likely to result is an overload on the V5.2 interface. When this is the case, calls from other subscribers connected to the access node may be congested and fail to be set up. An expedient proposed as a solution to this problem is to set up a direct connection from the access node to the remote access unit. However, the problem is that such a connection is not supported by the V5 standard, which means that several independent and mutually incompatible methods are used to set up the connection. Moreover, the operator encounters problems in trying to adapt different manufacturers"" implementations to each other. In normal telephonic calls, when the subscriber starts a call, the access node sends a call start signal via the V5 interface to the local exchange, and the local exchange controls the call process, connects the dial tone, receives the dialing, takes care of the metering, etc. In the case of Internet calls, the access node must handle the routing of the call to the data network independently without the local exchange participating in it.
The object of the present invention is to eliminate the drawbacks described above
A specific object of the present invention is to produce a new type of procedure and system in which data connections from subscribers connected to an access node can be set up without congesting the normal telephone network and telephone service.
Another object of the present invention is to produce a simple arrangement for improving the capacity of a telephone network especially to meet the needs of data communication over the telephone network, an arrangement that can be easily implemented using existing standardised technology.
A further object of the present invention is to disclose an arrangement for establishing a data connection that is applicable for all subscriber types, such as those using ISDN and POTS technology. It is also an object of the invention to enable an existing telephone network, especially an access network, to be updated so as to improve its support for data connections using normal telephone network operation control commands without any complex changes in systems or software.
As for the features characteristic of the invention, reference is made to the claims.
A telecommunication system preferable in respect of the invention comprises a telephone exchange, an access node connected to the telephone exchange via a standard V5 interface, and a data network, such as the Internet network or equivalent. Moreover, an embodiment of the system may comprise a remote access unit (RAS, Remote Access Unit), disposed e.g. between the access node and the Internet. In this case, the procedure of the invention allows a direct data connection to be set up between the access node and the data network from a terminal device connected to the access node. There may be a number of direct connections from the access node to the data network and/or remote access unit.
According to the invention, a data network subscriber is analyzed in the access node, and when the data network subscriber starts call setup, this is not signalled to the local exchange according to the normal V5 practice. Further, the signaling of the data network subscriber, of which there may be more than one, is primarily handled in the access node. This means that the call setup request is handled locally in the access node, where also a dial tone is generated for the data network subscriber. Based on the dialing given by the data network subscriber, a data connection between the data network subscriber and the data network is set up directly from the access node. However, if the subscriber dials an external line code or equivalent, then the call setup request will be transmitted to the local exchange in the normal manner.
As compared with prior art, the invention has the advantage that the procedure of the invention is applicable to all subscriber lines (POTS, ISDN) that use a circuit-switched service. As the subscriber signaling of data network or Internet subscribers is always primarily handled by the access node and subscriber signaling is only transmitted to the local exchange after the analysis of a normal call code or prefix or an external line code, ordinary subscribers analyzed in the access node can act just as before, in other words, they need not use an xe2x80x98external linexe2x80x99 code when making a call. The signaling of ordinary subscribers is not handled in the access node, but it is passed transparently and directly to the local exchange in accordance with the V5 specifications.
Subscribers can easily be converted into Internet subscribers because only operation control commands are needed, provided that a link from the access node to the Internet network has been built. In addition, no new cables need to be installed for the data network subscriber.
The solution of the invention reduces the load on the local exchange and transmission links. Moreover, the V5 interface is a standard interface and this solution does not require the local exchange to have any special functions because the local exchange takes no part in data calls beyond receiving a signal indicating that the subscriber is busy. The local exchange is notified of the non-availability of the subscriber by existing methods, such as the Control protocol of the V5 interface. However, the V5 standard does not in itself cover or support a switched data call from the access node. The subscriber can go on using all the existing functions and he/she need not get a second telephone line for the Internet. In addition, the subscriber may still set up e.g. a modem connection via the normal telephone network.
A further advantage provided by the invention is that, for an Internet subscriber, the only difference to the old line is that, when making a telephone call to the ordinary telephone network, he/she must dial a normal-call code or an external-line code before the telephone number to get the dial tone generated by the local exchange and to have the call set up normally via the V5 interface.
From the operator""s point of view, the invention provides the advantage that savings are made as resources are not reserved because of Internet traffic. In addition, the same access node may contain subscriber lines of more than one Internet operator.
In an embodiment of the present invention, a request from a data network subscriber for the setup of a voice call and/or data connection is analysed and, if it is discovered that the data network subscriber is setting up a data connection to a data network, then the group switch of the access node is instructed to set up a data connection using a link between the access node and the data network.
In a preferred case, after the data network subscriber has been connected to the data network, the local exchange is sent a signal indicating that the data network subscriber is busy. Thus, the local exchange is able to keep a record of the status of the data network subscribers connected to the access node and is therefore able to act in an appropriate manner in any given situation. Further, after the data network subscriber has disconnected a data connection to a data network, the local exchange is sent a signal indicating that the data network subscriber is available. These signals can be given e.g. using the normal V5 interface signaling protocol, such as the Control protocol.
If a data network subscriber is setting up a normal voice call, then the data network subscriber""s call setup request is provided with a prefix, generally a selection entered via the terminal device, by which the access node identifies the call as a normal call. Based on the prefix, a notice about the data network subscriber""s call setup request is sent to the local exchange, which starts call control in a manner consistent with the V5 specifications.